Hello here is me making a random grepper answer:

Hi All if you are getting this error:
error: Error [firebase_auth/internal-error] {"error":{"code":400,"message":"API key not valid. Please pass a valid API key.","errors":[{"message":"API key not valid. Please pass a valid API key.","domain":"global","reason":"badRequest"}],"status":"INVALID_ARGUMENT","details":[{"@type":"type.googleapis.com/google.rpc.ErrorInfo","reason":"API_KEY_INVALID","domain":"googleapis.com","metadata":{"service":"identitytoolkit.googleapis.com"}}]}}
this means you are trying to run app on web chrome and in your flutter app this is not configure so follow below steps: 1. Go to https://console.firebase 2. Select your project name i.e. "E-Commerce App" 3. Select Add App option from dashboard select platform (flutter/android/ios/web) from this select flutter 4. Add Firebase to your Flutter app this screen will open then select next 5. From any directory, run this command:"dart pub global activate flutterfire_cli" 6. Then, at the root of your Flutter project directory, run this command:"flutterfire configure --project=eshop-a44ca" 7. After "flutterfire configure" check npm
add this in main.dart file:
await Firebase.initializeApp( options: DefaultFirebaseOptions.currentPlatform, ); 8. Run this command in your project directory npm install -g firebase-tools
9.Again run this command ""flutterfire configure --project=eshop-a44ca" you will see below screen [firebase options file created in lib folder] 9. now you can sign up/register user successfully 10. [user created on firestore database ] [1]: https://i.stack.imgur.com/NBiDz.png